Doc for consensus engine

[adi-g15]

Hi,
I am currently doing an internship related to blockchain where we learned to work with sawtooth.
Since I was editing the devmode, I wrote a documentation for consensus engine for future reference, since it wasn't there i took devmode code for reference, it's more of my own notes (mostly complete for the code part) - https://github.com/adi-g15/notes/blob/main/hyperledger/sawtooth/consensus-engine/docs-rust.md

In case that doc can help, i would be pleased to add/edit its contents 😅 .